Review
Forestry
Christopher J. Fettig, Jackson P. Audley, Crystal S. Homicz, Robert A. Progar
Summary: Western pine beetle is a major cause of ponderosa pine mortality in western North America, and current epidemics are among the largest ever recorded. Researchers have studied the chemical ecology of western pine beetle and developed a semiochemical repellent called Verbenone Plus, which has been proven effective in protecting ponderosa pines from beetle-induced mortality in multiple studies.
Article
Environmental Sciences
Zachary J. Robbins, Chonggang Xu, Alex Jonko, Rutuja Chitra-Tarak, Christopher J. Fettig, Jennifer Costanza, Leif A. Mortenson, Brian H. Aukema, Lara M. Kueppers, Robert M. Scheller
Summary: Outbreaks of bark beetle species can rapidly develop in response to drought, leading to a transfer of stored carbon from live trees to dead trees and subsequent release into the atmosphere. The western pine beetle outbreak in California may indicate more frequent and severe outbreaks as temperatures rise and droughts increase. However, predicting the frequency and severity of beetle outbreaks is challenging due to complex interactions between beetles, tree populations, and climate. Projections suggest that the carbon stored in live trees will not return to pre-drought levels due to future beetle outbreaks, but the range of outbreak frequencies and severities varies among climate models. Total plot basal area, drought severity, and temperature are significant factors affecting the mortality rate of trees, and reducing high stand basal area may mitigate the severity of future outbreaks.
FRONTIERS IN ENVIRONMENTAL SCIENCE
(2023)
Article
Forestry
Christopher J. Fettig, Leif A. Mortenson, Jackson P. Audley
Summary: After thinning and prescribed burning in ponderosa pine forests in Oregon, USA, causes of tree mortality mainly included prescribed fire and various species of bark beetles. Tree mortality levels were significantly higher in high density stands compared to the untreated control.
Article
Plant Sciences
Nadir Erbilgin, Leila Zanganeh, Jennifer G. Klutsch, Shih-hsuan Chen, Shiyang Zhao, Guncha Ishangulyyeva, Stephen J. Burr, Monica Gaylord, Richard Hofstetter, Ken Keefover-Ring, Kenneth F. Raffa, Thomas Kolb
Summary: The research showed that only trees that were both root-trenched and attacked by bark beetles depleted carbohydrates and died during the first year of attacks. Live trees contained higher carbohydrates than dying trees, but levels of diterpenes did not vary between the two groups. This suggests that reallocation of carbohydrates to diterpenes during early stages of beetle attacks is limited in drought-stricken trees, and combination of biotic and abiotic stress leads to tree death.
PLANT CELL AND ENVIRONMENT
(2021)
Article
Forestry
Paul J. Chisholm, Camille S. Stevens-Rumann, Thomas Seth Davis
Summary: In temperate coniferous forests, the probability of tree mortality during bark beetle outbreaks is influenced by factors such as tree diameter, stand density, and elevation. The study found that mortality rates were lower in trees with higher live crown ratios, and rose with increasing tree diameter, stand basal area, and elevation. The association between elevation and mortality risk was buffered by precipitation, with dry high-elevation stands experiencing more mortality than moist high-elevation stands. Tree diameter, crown ratio, and stand density affected tree mortality independent of precipitation.
Article
Biochemistry & Molecular Biology
Veronica Torres-Banda, Gabriel Obregon-Molina, L. Viridiana Soto-Robles, Arnulfo Albores-Medina, Maria Fernanda Lopez, Gerardo Zuniga
Summary: Dendroctonus bark beetles, the most destructive agents in coniferous forests, have molecular mechanisms to counteract the toxic compounds of their host's chemical defenses. By comparing the gut response of two sibling species of bark beetles after being stimulated with a blend of their main kairomones, differences in digestive process and xenobiotics metabolism were observed. The results suggest that terpenes metabolism is accompanied by an adaptive response, involving the activation of other metabolic pathways, to ensure energy supply and survival specific to each species based on their life history and ecological strategy.
COMPUTATIONAL AND STRUCTURAL BIOTECHNOLOGY JOURNAL
(2022)
Article
Ecology
Vanessa Agbulu, Rashaduz Zaman, Guncha Ishangulyyeva, James F. Cahill, N. Erbilgin
Summary: This study showed that host defense metabolites impact the suitability of hosts to bark beetles by influencing their fungal symbionts, and different species of fungal symbionts respond differently to host monoterpene blends.
Article
Plant Sciences
Kyle C. Rodman, Robert A. Andrus, Amanda R. Carlson, Trevor A. Carter, Teresa B. Chapman, Jonathan D. Coop, Paula J. Fornwalt, Nathan S. Gill, Brian J. Harvey, Ashley E. Hoffman, Katharine C. Kelsey, Dominik Kulakowski, Daniel C. Laughlin, Jenna E. Morris, Jose F. Negron, Katherine M. Nigro, Gregory S. Pappas, Miranda D. Redmond, Charles C. Rhoades, Monique E. Rocca, Zoe H. Schapira, Jason S. Sibold, Camille S. Stevens-Rumann, Thomas T. Veblen, Jianmin Wang, Xiaoyang Zhang, Sarah J. Hart
Summary: Recent outbreaks of native bark beetles have significantly impacted tree mortality in subalpine forests of the US Rocky Mountains. Although most areas are likely to recover to pre-outbreak tree densities, changes in species composition may persist due to regional variability.
JOURNAL OF ECOLOGY
(2022)
Article
Forestry
Fatima M. Mendez-Encina, Jorge Mendez-Gonzalez, Rocio Mendieta-Oviedo, Jose O. M. Lopez-Diaz, Juan A. Najera-Luna
Summary: This study generated ecological niche models and evaluated the climate suitability overlap between bark beetles and pine trees, finding that Dendroctonus mexicanus is expanding into climates not currently occupied by the studied pine species.
Article
Multidisciplinary Sciences
Michael J. Koontz, Andrew M. Latimer, Leif A. Mortenson, Christopher J. Fettig, Malcolm P. North
Summary: The study analyzed data and found an interaction between host size and climatic water deficit, resulting in higher mortality rates for large trees in dry, warm conditions, but not in cooler or wetter conditions.
NATURE COMMUNICATIONS
(2021)
Article
Environmental Sciences
Alexandra Howell, Mario Bretfeld, Erica Belmont
Summary: This study compared and analyzed the combustion of healthy trees and trees killed by bark beetles in a forest fire in southeast Wyoming, USA, to explore the impact of beetle-induced mortality on carbon. Results showed that PyC production and energy output in beetle-killed boles were significantly higher than in healthy boles.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Microbiology
Tian Cheng, Tereza Veselska, Barbora Krizkova, Karel Svec, Vaclav Havlicek, Marc Stadler, Miroslav Kolarik
Summary: Spruce bark beetle Ips typographus can cause outbreaks and significant losses in the forest industry. Symbiotic microorganisms inhabiting the beetle's gut play a role in detoxification of plant secondary metabolites, plant cell wall degradation, and improvement of beetle's nutrition. Genome analysis of gut yeasts Kuraishia molischiana, Cryptococcus sp., Nakazawaea ambrosiae, Ogataea ramenticola, and Wickerhamomyces bisporus revealed diverse gene families related to detoxification processes and synthesis of essential nutrients.
FRONTIERS IN MICROBIOLOGY
(2023)
Article
Plant Sciences
Aziz Ullah, Jennifer G. Klutsch, Nadir Erbilgin
Summary: Intraspecific variation in conifers has been studied in terms of defense against herbivores and pathogens, showing the influence of different compounds on insects and microbes. Research on biologically relevant defense compounds among tree populations is necessary. Variation in lodgepole pine monoterpenes was characterized in a progeny trial, revealing different effects on the mountain pine beetle and its fungal symbiont. The study highlights a co-evolutionary arms-race resulting in complementary defense metabolites among pine populations to enhance tree survival.
PLANT CELL AND ENVIRONMENT
(2021)
Article
Microbiology
Diana L. Six, Kier D. Klepzig
Summary: Context dependency refers to shifts in biological interactions based on genetic, abiotic, and biotic context. Mutualism models often focus on the sliding scale of interaction outcomes as environmental conditions change, but fail to address mutualisms rooted in by-product benefits or lacking antagonistic alternate states. Bark beetle-fungus symbioses exemplify these unique mutualisms, with species co-constructing niches based on by-product benefits to thrive in otherwise challenging environments. These partnerships highlight the importance of understanding how environmental variability impacts mutualism strength, stability, and ecological roles.
FRONTIERS IN MICROBIOLOGY
(2021)
Article
Ecology
Rebecca B. Wayman, Hugh D. Safford
Summary: The study found that in mixed-conifer forests in California's Sierra Nevada, there is a relationship between wildfire severity and severity of prefire tree mortality, and this relationship may vary under different weather conditions.
ECOLOGICAL APPLICATIONS
(2021)
Article
Zoology
Carol L. Bedoya, Richard W. Hofstetter, Ximena J. Nelson, Michael Hayes, Daniel R. Miller, Eckehard G. Brockerhoff
Summary: Bark and ambrosia beetles and pinhole borers are two subfamilies of weevils that use acoustic communication within plant tissue. Research has found that 33% of collected species produce sounds, with 60% of these sounds being previously unreported. Mating system type and size appear to play an important role in determining the acoustic communicatory capacity of most species.
BIOACOUSTICS-THE INTERNATIONAL JOURNAL OF ANIMAL SOUND AND ITS RECORDING
(2021)
Article
Ecology
David N. Soderberg, Karen E. Mock, Richard W. Hofstetter, Barbara J. Bentz
Summary: The study investigated the genetic and environmental adaptability of mountain pine beetles to climate change, finding that both populations could thrive in warmer climate conditions, with the highest reproductive success occurring in low-elevation areas, suggesting that southward migration may not be temperature limited.
ECOLOGICAL MONOGRAPHS
(2021)
Article
Entomology
Derek Uhey, Karen Haubensak, Richard Hofstetter
Summary: Research along elevational gradients in northern Arizona revealed that ground-dwelling arthropods show peak diversity at mid-elevations, with abundance, richness, and diversity indexes peaking in this region. Community composition varies significantly across the gradient, driven by shifts from ants dominating low to mid elevations, and beetles dominating high elevations. Population turnover is high among sites, suggesting vulnerability to environmental change, especially at lower elevations in arid regions.
ENVIRONMENTAL ENTOMOLOGY
(2021)
Article
Biochemistry & Molecular Biology
Brian T. Sullivan, Amanda M. Grady, Richard W. Hofstetter, Deepa S. Pureswaran, Cavell Brownie, Daniel Cluck, Tom W. Coleman, Andrew Graves, Elizabeth Willhite, Lia Spiegel, Dwight Scarbrough, Andrew Orlemann, Gerardo Zuniga
Summary: The study found that the semiochemical systems of Dendroctonus brevicomis and Dendroctonus barberi populations have diverged, confirming that they are separate, allopatric species.
JOURNAL OF CHEMICAL ECOLOGY
(2021)
Article
Entomology
Sneha Vissa, David N. Soderberg, Richard W. Hofstetter
Summary: Climate warming has significant effects on forest insect populations, particularly bark beetles, influencing the abundance of symbiotic mite communities associated with them. Mite populations show adaptation to local climates, impacting beetle reproduction and health. Understanding these patterns can provide insights into how climate change will affect beetle-mite associations in forest ecosystems.
Article
Biodiversity Conservation
Connor D. Crouch, Amanda M. Grady, Nicholas P. Wilhelmi, Richard W. Hofstetter, Daniel E. DePinte, Kristen M. Waring
Summary: Oystershell scale is an emerging invasive insect that poses a serious threat to quaking aspen in the southwestern US. Research indicates that the ongoing outbreak of Oystershell scale in northern Arizona is causing dieback and mortality in aspen stands. The potential high impact of Oystershell scale as an invasive insect comes from its hypothesized role as a sleeper species, potential interactions with climate change, and its polyphagous nature.
BIOLOGICAL INVASIONS
(2021)
Review
Forestry
Christine M. Mott, Richard W. Hofstetter, Anita J. Antoninka
Summary: Pile burning is favored for debris removal in coniferous forests, but its effects on soil, vegetation, and animals suggest a need for further research on ecosystem impacts and management strategies.
FOREST ECOLOGY AND MANAGEMENT
(2021)
Review
Entomology
Derek A. Uhey, Richard W. Hofstetter
Summary: Harvester ants, traditionally labeled as pests, are now recognized as keystone species that benefit ecosystem functioning and human activities through nest engineering and trophic interactions. Despite being perceived as harmful in their native ranges, modern research supports their numerous keystone roles and highlights the need for further study into their impacts on natural and managed systems.
ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA
(2022)
Article
Plant Sciences
Nadir Erbilgin, Leila Zanganeh, Jennifer G. Klutsch, Shih-hsuan Chen, Shiyang Zhao, Guncha Ishangulyyeva, Stephen J. Burr, Monica Gaylord, Richard Hofstetter, Ken Keefover-Ring, Kenneth F. Raffa, Thomas Kolb
Summary: The research showed that only trees that were both root-trenched and attacked by bark beetles depleted carbohydrates and died during the first year of attacks. Live trees contained higher carbohydrates than dying trees, but levels of diterpenes did not vary between the two groups. This suggests that reallocation of carbohydrates to diterpenes during early stages of beetle attacks is limited in drought-stricken trees, and combination of biotic and abiotic stress leads to tree death.
PLANT CELL AND ENVIRONMENT
(2021)
Article
Forestry
Bri Tiffany, Todd Chaudhry, Richard W. Hofstetter, Clare Aslan
Summary: Forest pest outbreaks that cross boundaries face challenges due to misalignment of management objectives and policies, federally mandated policies, lack of collaboration, and lack of public support. Strategies to improve outcomes include reevaluating policies, ensuring consistent messaging, and developing a cross-boundary management team. Increasing collaboration in multi-jurisdictional landscapes is crucial for preparing for future pest outbreaks.
Article
Biology
Zhudong Liu, Longsheng Xing, Wanlong Huang, Bo Liu, Fanghao Wan, Kenneth F. Raffa, Richard W. Hofstetter, Wanqiang Qian, Jianghua Sun
Summary: This study obtained a high-quality reference genome of the red turpentine beetle (RTB), which revealed rapidly expanding gene families and positively selected genes that may contribute to its environmental adaptation. The study also explored the population genetic structure and invasion routes of RTB in China, highlighting the enhanced environmental adaptability of Chinese populations.
Article
Forestry
Leo O'Neill, Peter Z. Fule, Richard W. Hofstetter
Summary: We reconstructed the historical outbreak regime of Pandora moths on the Kaibab Plateau and found that interruptions in the fire regime and climate oscillations were related to outbreak dynamics. Eleven outbreaks were detected between 1744 and the present, occurring at multiple sites and lasting for 10 years at 25-year intervals. Dry to wet climate changes were correlated with outbreak initiations. Pandora moth outbreaks appear to be intrinsic to the forest ecosystems of the Kaibab Plateau, but further research is needed to understand their effects on the ecosystem and their future under climate warming.
Article
Forestry
Christine Mott, Anita Antoninka, Richard Hofstetter
Summary: Increasing size, severity, and human proximity to fires in the western US drive a need for more effective ecosystem restoration post-fire. Few studies have investigated the impact of surface treatments, such as mastication of logging slash, on arthropod communities. This study found that predatory beetles were more abundant in mulch treatments in a large landscape-scale fire, while fungivores had no significant preference for mulch and several native bark beetles were more abundant in untreated sites. The size of the fire footprint and distance to the intact forest matrix likely impact arthropod community composition over time.
Article
Entomology
Derek A. Uhey, Sneha Vissa, Karen A. Haubensak, Andrew D. Ballard, Mekeilah B. Aguilar, Richard W. Hofstetter
Summary: Harvester ants create habitats along nest rims, which provide refugia for plants during drought and grazing. The study finds that nest rims increase vegetation cover and support both native and exotic plant species. The results suggest that harvester ants play important roles in both invasion ecology and restoration.
ENVIRONMENTAL ENTOMOLOGY
(2023)
Article
Entomology
Derek A. Uhey, Matthew A. Bowker, Karen A. Haubensak, David Auty, Sneha Vissa, Richard W. Hofstetter
Summary: Understanding the impact of elevation on biodiversity requires considering habitat types. This study compared ground-dwelling arthropods in open- and forested-habitats along an elevational gradient. The results showed that the relationship between animal diversity and elevation can be mediated by habitat type and that different functional and taxonomic groups exhibit different patterns.
JOURNAL OF INSECT SCIENCE
(2022)
